Lifting-jack.



0. L. CBABB.

LIFTING JACK.

APPLICATION FILED JAN. 30. 1912. 1,1 32,075, Patented Mar. 16, 1915.

mi nesses THE NORRIS PETERS CO; PHOTCLITHII, WASHINGTOIY. D- C- UNITED STATES PATENT OFFICE.

CHARLES L. CRABIB, OF MILLING'ION, NEW JERSEY, ASSIGNOR TO TOPPING- BROTHERS, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

LIFTING-J'ACK.

Specification of Letters Patent.

Patented Mar. 16, 1915.

Application filed January 30, 1912. Serial No. 674,301.

To all whom it may concern Be it known that I, CHARLES L. CRABB, a citizen of the United States, and resident of Millington, in the county of Morris and State of New Jersey, have invented a new and useful Improvement in Lifting-Jacks, of which the following is a specification.

In lifting jacks as ordinarily constructed, the upper telescoping member and the head have been formed integral, thus requiring the construction of jacks of various heights to suit different requirements, so that too great a movement of the upper member on the lower member is obviated.

The object of the present invention is to enable jacks of a standard size to be adapted for use in connection with requirements for different heights by the interchanging of removable heads carried by the upper member of the jack.

A practical embodiment of the invention is represented in the accompanying drawings in which, Figure 1 shows a lifting jack partly in perspective and partly in section, with a short removable head secured to the upper telescoping member, and Fig. 2 is a detail similar view showing a long head secured to the upper member of the jack.

The lower member of the jack is denoted by 1 and it is provided with a suitable base 2. This lower member is also provided with a nut 3, through which the screw threaded portion 40f a lifting screw 5 works. The upper member 6 of the jack telescopes over the lower member 1. Means are provided for turning the screw to raise and lower the jack, which means includes an operating shaft 7 mounted in suitable bearings 8 carried by a plate 9 secured to the upper member 6, which shaft has a bevel gear 10 fixed to its inner end within the upper member 6, and meshing with a bevel gear 11 fast on the screw 5, near the top of the screw. The top of the upper member 6 is open and is provided with a reduced exteriorly screw threaded flange 12. The removable heads are denoted by 13. These heads are preferably made hollow for reducing their weight. These heads are provided with interiorly screw-threaded peripheral flanges 13* arranged to screw on to the exteriorly screw threaded flange 12 of the upper member 63. The removable head 13 is supported upon the screw 5. In the present instance an antifriction bearing comprising the rows of balls 14 and bearing plates 15, 16, is interposed between a downwardly extended portion 17 of the head 13 and the back of the bevel gear 11. This downwardly extended portion 17 of the head fits snugly within the flange 12 and is provided with a bore 18 into which the reduced upper end 19 of the screw 5 extends. This head thus forms a lateral support for the top of the screw 5.

The advantage of the structure hereinabove described lies in the fact that if a jack of a certain height is desired, a head of a certain height can be quickly and read ily secured to the upper member of the jack to comply with the conditions.

It will be seen that by varying the height of the removable head, the height of the jack may be varied between very wide limits.

What I claim is:

A lifting jack comprising an upper member provided with a reduced exteriorly screw-threaded flange, a lower member, a screw carried by the lower member, means for turning said screw carried by said upper member, a removable head provided with an interiorly screw-threaded flange and a downwardly extended portion arranged to engage the outside and inside respectively of the reduced flange of the upper member, said downwardly extended portion forming a lateral support for the upper end of the screw.

In testimony, that I claim the foregoing as my invention, I have signed my name in presence of two witnesses, this eighteenth day of January 1912.

CHARLES L. CRABB.

Witnesses:

F. GEORGE BARRY, HENRY O. THEME.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents.

Washington, I). 0. 

